The recruitment of basophils into delayed-in-time reactions has been recently described and has opened a vitally important area of research into basophil function. The regulation of these cells in delayed reactions has been shown to be under the control of both immune lymphocytes and immune serum. This research proposal submits a comprehensive program for the investigation into the immune mechanisms controlling the basophil recruitment. Since it has been shown that it is the 7SIgGl antibody in serum that can mediate cutaneous basophil hypersensitivity (CBH), our hypotheses hold it is the Fc portion of this molecule that is important in the mediation of cutaneous basophil responses. Cutaneous basophil hypersensitivity reactivity resembles the newly recognized IgE mediated late component of immediate anaphylactic hypersensitivity reactions. Studies have been designed to evaluate the possibility that guinea pig IgE can mediate CBH as a model for the human late reactions. Experiments have also been proposed to look into the question of the interrelationship of T-cells and B-cells in the regulation of CBH. The possibility that T-cell transfers of basophil responses are dependent on contaminating donor B-cells or B-cells in the recipients will be investigated. Finally, knowledge that we have gained in the regulation of basophils in delayed reactions will be applied to the study of CBH as an alternate mechanism of tumor resistance in the host.